Don,
You have already received some good advice from Joe, Brian and Lee.

In my opinion, no an ionic cleanliness tester is enough.  We have them in
all of our facilities.  We have not failed a test in 15 years.  We continue
to do it because our customers what to see some form of cleanliness
monitoring.  It makes them happy, so it makes us happy.

The J-Std-001 approach is one way to do a process qualification.  Newer
methods are being developed, but may not quite be ready for prime time.
If you are manufacturing commercial avionics, as we are, you are probably
familiar with the DO-160 document, levied by the FAA.  We run those tests
whenever we qualify a new product.  I would suggest you run ion
chromatography, as well as Omegameter, on samples that then are qualified
in the DO-160 tests.  The humidity tests will be the most telling.  If
desired, you can take the 10 day worst case humidity test and extend it
out.  If you are producing military avionics, as we are, then the same
approach applies for Mil-Std-883 tests.  Doing IC gives you a good idea of
what residues are present.  The ionic cleanliness tester tells you its
metric for the product, which you can then use as a target for process
control.  The functional tests tell you if those levels of cleanliness are
adequate for your product in your end-use environment.

Doing it this way means your data is 100% relative.  Going the J-STD-001
route you have to interpret how much the lab data approximates real world
data.  Always an iffy proposition.

And Brian, we already established last year that a piece of string is 8.4
cm long.  So stop asking that question.

Doug Pauls




             Donald Vischulis
             <dvischulis@EARTH
             LINK.NET>                                                  To
             Sent by: TechNet          [log in to unmask]
             <[log in to unmask]>                                          cc

                                                                   Subject
             03/09/2006 04:58          [TN] Cleaning Qualification
             PM                        Question


             Please respond to
             Donald Vischulis
             <dvischulis@earth
                 link.net>






All

I've been assigned the task of determining if a supplier's current cleaning
process is robust or if additional testing is required to be able to say
that the product is clean enough to provide years of field use.  The board
is a 2-sided Class 3 assembly (95% SMT) with one BGA and about 1500 other
components. The assembly is soldered with a water soluble flux, it's
cleaned in a batch cleaner with DI water, and is conformal coated.  The
current manufacturer is using and Omega meter to verify the cleanliness of
the board after cleaning.

My questions:

Is this process good enough to provide a reliable product in an aircraft
application?
If not what guidance is available to determine what level of process
qualification is needed to answer question #1?

Any help is really appreciated.

Don Vischulis

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